Long-distance travels are a drain on both your time and money. The fact that such journeys can also seriously mess with your sleep and energy schedule—leaving your brain feeling like a moldy marshmallow—is insult added to injury. But with science, discipline, and math, the biological injustice of jet lag can be tamed.

The quick and dirty version: On the day of your flight, you fast for 12-16 hours before breakfast time in your destination. With the help of Gawker Media’s in-house tech guru Adam Pash, we’ve simplified figuring out the logistics with Flygirl’s Anti-Jet Lag Calculator. Enter your points of departure and arrival, and our handy calculator will crunch time zone numbers and tell you when to stop and resume eating based on a 14-hour fast. Stick to the plan, avoid snacks (no more than a tiny handful of nuts, if you must), and you’ll be golden.

Jet lag is a disruption to the body’s circadian rhythms (which dictate our sleep schedule) caused by speedy travel across multiple time zones. The effects include fatigue, irregular sleep patterns, and general stupidity. Worse, getting back to biological and mental normalcy can take several days of adjustment when in a new time zone. Ain’t nobody got time for that.

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There are various methods of preparation in order avoid winding up in this hellscape, most of which revolve around light exposure, sleep schedules, and melatonin pills. These approaches can be helpful, but they’re hardly kryptonite. But a form of kryptonite does exist: it’s your diet.

The Argonne Anti-Jet Lag diet was invented by scientist Charles Ehret, who concluded that our biological clocks are partially dictated by our stomachs; he found that irregularly timed meals of varying size and composition “gradually unmoored” the body’s biological clock. According to Harpers, the Argonne diet has been used to great effect by the Army, Navy, CIA, Canadian National Swim Team, and the Mormon Tabernacle Choir. If hundreds of singers sweating through their temple garments are wrong, you don’t want to be right.

The problem with the Argonne diet is that it requires multiple days of adherence to a wacky dining schedule in advance of your trip: lots of feasting and fasting, etc. Harvard researchers, however, have pared it down to something more manageable: an anti-jet lag fast. And it works.

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Here’s how you do it: Figure out breakfast time in your destination—for our purposes, we’re going to say that’s 8:30 am—and, for 12-16 hours before that hour, you fast (water is fine). When it’s finally 8:30 am in your destination time zone, you resume eating as normal. So, for example:

I’m flying from Chicago to Barcelona.

8:30 am in Barcelona is 1:30 am in Chicago.

If I can resume eating at 1:30 am central time, I need to start my fast 12-16 hours in advance of that. So I stop eating at some point between 9:30 am and 1:30 pm central on the day of my flight.

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Or you can just enter some basic information into the calculator above, and we’ll figure all that out for you.

The fast is simple but highly effective: I’ve done the fast when flying abroad five or six times now, and I’ve been immediately able to sleep on schedule in my destination. (If I cheat and have a little snack, however, it doesn’t work quite so well.) I’ve had friends report similar success, and Harpers writer Steve Hendricks is a convert.

Next time you’re facing a flight across multiple time zones, use our calculator and give the fast a try — we look forward to you joining us in a globe-trotting world free of brain fog and sleepless misery.

Flygirl is Jezebel’s travel blog dedicated to adventures big and small, tips and tricks for navigation, and exploring the world at large. Have a story or an idea? We’re always taking submissions; email us with “Flygirl” AND your topic in the subject line. No pitches in the comments, please.